index.js

const cluster = require('cluster');
const express = require('express');
const morgan = require('morgan');
const uuid = require('uuid');
const bodyParser = require('body-parser');
const app = require('./app');

const log = app.logger;
const server = express();

// enable CORS in development
if (app.config.isDevelopment) {
  server.use((req, res, next) => {
    res.header('Access-Control-Allow-Origin', '*');
    res.header(
      'Access-Control-Allow-Headers',
      'Origin, X-Requested-With, Content-Type, Accept, Authorization',
    );
    res.header(
      'Access-Control-Allow-Methods',
      'GET, PUT, POST, PATCH, DELETE, OPTIONS',
    );

    if (req.method.toLowerCase() === 'options') res.status(200).end();
    else next();
  });
}

// Assign a unique ID to each request
server.use((req, res, next) => {
  req.id = uuid.v4().split('-').pop();
  res.set('X-Flow-Id', req.id);
  next();
});

// Enable logging for debugging and tracing purposes
server.use(
  morgan(
    ':date[web] [IP :req[X-Forwarded-For]] [Flow :res[X-Flow-Id]] :method :url :status :response-time[3]ms',
  ),
);

// Parse urlencoded and json POST data
server.use(bodyParser.urlencoded({ extended: true }));
server.use(bodyParser.json());

// Route the API
server.use('/app/api', app.api.router);

// Register error middleware
server.use(app.db.errorHandler);
server.use(app.error.errorHandler);
server.use(app.error.notFoundHandler);

// perform DB initialization once
const setup = app.db.setup(true, app.config.isDevelopment);

if (require.main == module) {
  // Create workers
  if (cluster.isMaster) {
    log.debug('Creating %d cluster workers...', app.config.numCPUs);
    for (let i = 0; i < app.config.numCPUs; i++) cluster.fork();

    cluster.on('exit', (worker, code, signal) => {
      log.info(
        'Worker PID %s died (%s). Restarting...',
        worker.process.pid,
        signal,
      );
      console.log("FORKING");
      cluster.fork();
    });
  }
  if (!cluster.isMaster) {
    // Start the server on each worker
    server.listen(app.config.port, app.config.host, async () => {
      log.info(
        'Started server %s on port %d, PID: %d',
        app.config.host,
        app.config.port,
        process.pid,
      );
    });
  }
}
else {
  let HTTPserver = server.listen(app.config.port, app.config.host, () => {
    log.info(
      'Started TEST server %s on port %d, PID: %d',
      app.config.host,
      app.config.port,
      process.pid,
    );
  });
  module.exports = { server: HTTPserver, setup };
}